WASHINGTON – Sen. Hillary Rodham Clinton is becoming more and more of a PAC-rat, using her political-action committee’s cash to build her own political network rather than to boost other Democrats.

Last year, HILLPAC gave only 31 percent of what it raised to other candidates; this year, that figure is down to 20 percent. That means she’s spent $4 out of every $5 on her own political operation.

In all, HILLPAC spent $589,000 in the first half of this year – and only $120,000 of that went to other Democrats. Most went for Clinton’s staff, fund-raising, legal fees and travel.

Critics say personal PACs like HILLPAC let lawmakers double dip and effectively exceed legal limits by raising cash twice from the same source – once for their own campaign and once for the PAC – and then spend both on themselves.

In Clinton’s case, it’s hard to tell the difference between HILLPAC and her own campaign committee, Friends of Hillary, since both have the same address, the same 16 staffers and pay the same communications consultant.

Last night, the New York senator was already looking to 2006 as she kicked off her re-election bid with a posh party feting deep-pocketed donors of campaigns past – and, hopefully, future.

A steady caravan of BMWs, Lexuses and Mercedes pulled up around 6 p.m. to the tony Chappaqua home Clinton shares with ex-president hubby Bill. The guests were immediately greeted by valet workers dressed in white dinner jackets and quickly whisked inside.

Both Clintons schmoozed and mused with the crowd – more than 100 of the senator’s most generous campaign contributors and top fund-raisers from the 2000 race – for 2½ hours.

While Sen. Clinton says she’s shelved a possible plans for a White House run in 2004, aides said she is far from shying away from the national political spotlight.